For Mammography: Baseline at 40 Makes Sense

February 9, 2021
Whitney J. Palmer

Study shows that baseline mammography screening to identify breast density, starting at age 40, is cost-effective.

When it comes to mammography, it is cost-effective to start baseline screening for women at age 40, according to newly published research.

In a Feb. 9 Annals of Internal Medicine study, investigators from the University of Texas MD Anderson Cancer Center assessed seven mammography screening situations. Based on their evaluations, they found that, for average-risk women, capturing a baseline mammogram at age 40 is both clinically and economically sound.

“Compared with other screening strategies examined in our study, this strategy is associated with the greatest reduction in breast cancer mortality and is cost-effective but involves the most screening mammograms in a woman’s lifetime and higher rates of false positive results and over-diagnosis,” said the team led by Ya-Chen Tina Shih, Ph.D., chief of cancer economics and policy at MD Anderson.

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To reach this conclusion, the team evaluated seven breast cancer screening strategies: no screening, biennial screening between ages 50 and 75, triennial screening between 50 and 75, and four density-stratified strategies – two with baseline mammogram at age 40 and two at age 50. Dense-stratified strategies were assigned to women with dense breasts and biennial or triennial strategies starting at age 50 were used with women with non-dense breasts.

According to the team, this U.S. National Cancer Institute-funded study was intended to examine the costs and possible harms that come with pinpointing which women have dense breasts at age 40. Breast density is a known breast cancer risk factor, however, and providers have been mandated to alert women to their density status since February 2019. But, because of current guidelines, some women may not get this information until age 50.

Right now, the U.S. Preventive Services Task Force (USPSTF) recommends biennial screening starting at age 50 – a guideline contradicted by the finding from Shih’s team. Recently, though, the USPSTF announced it is re-examining its guidelines, using more updated, comprehensive data.

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For this study, Shih’s team used a microsimulation model to evaluate and compare the seven strategies, diagnostics and treatments, diagnoses, and mortality, modeling outcomes for 500,000 average-risk women born in 1970. They defined density, which affects roughly 50 percent of women in the United States, as BI-RADS C and D.

Based on their evaluation, baseline screening age at 40 was preferred, followed by annual screenings for dense-breast women ages 40 to 75 and biennial screening for non-dense breast women between ages 50 and 75. Their evaluation showed a cost-effectiveness ratio of $32,600 per quality-adjusted life year (QALY) compared with the 50-to-75 biennial strategy. A $100,000 per QALY threshold is typically acceptable nationwide.

Following this baseline-at-40 recommendation sets patients and providers up for potentially better outcomes. Armed with more information, they can make better life-time screening decisions, the team said.

“This baseline assessment can be expanded to collect other information, such as family history or polygenic risk scores, to further develop a risk profile that allows more targeted and personalized screening,” they wrote.

However, for some experts, the cost and potential for over-diagnosis was too high. In an accompanying editorial, Karla Kerlikowske, M.D., professor of medicine and epidemiology, and Kirsten Bibbins-Domingo, M.D., Ph.D., professor and chair of epidemiology, -- both from the University of California at San Francisco – advocated for maintaining an age-50 start date for baseline mammography and biennial screening to age 75 for average-risk women.

Only 24 percent of women with dense breasts have a high risk for a missed invasive cancer within a year of a negative mammogram, they said, and Shih’s study inflated the benefit from mammography screening compared to other studies, as well as overstated the number of avoided deaths, they added.

Consequently, they called for overall risk screening – breast density, age, family history, and breast biopsy history – to maximize mammography benefits while controlling any potential harms to the patient.

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